/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// The original code is from https://github.com/netguy204/gambit-game-lib
#include <jni.h>
#include <assert.h>
#include "android_fopen.h"
#include <errno.h>
#include <android/asset_manager.h>
#include <android/asset_manager_jni.h>

static int android_read(void *cookie, char *buf, int size) {
    return AAsset_read((AAsset *) cookie, buf, size);
}

static int android_write(void *cookie, const char *buf, int size) {
    return EACCES; // can't provide write access to the apk
}

static fpos_t android_seek(void *cookie, fpos_t offset, int whence) {
    return AAsset_seek((AAsset *) cookie, offset, whence);
}

static int android_close(void *cookie) {
    AAsset_close((AAsset *) cookie);
    return 0;
}

FILE *android_assets_fopen(JNIEnv *env, jobject asset_manager, jstring filename) {
    AAssetManager *android_asset_manager = AAssetManager_fromJava(env, asset_manager);

    const char *fname = (*env)->GetStringUTFChars(env, filename, NULL);
    if (fname == NULL) {
        (*env)->ReleaseStringUTFChars(env, filename, fname);
        return NULL;
    }

    FILE *file = android_fopen(android_asset_manager, fname, "rb");
    (*env)->ReleaseStringUTFChars(env, filename, fname);
    return file;
}

FILE *android_fopen(AAssetManager *android_asset_manager, const char *fname, const char *mode) {
    if (mode[0] == 'w') {
        return NULL;
    }

    AAsset *asset = AAssetManager_open(android_asset_manager, fname, 0);
    if (!asset) {
        return NULL;
    }

    return funopen(asset, android_read, android_write, android_seek, android_close);
}